907-0601-00 Rev. C Model 907 Video/Data Multiplexer – User’s Guide
Focal Technologies Corp. Page 5-4
5.3 907-485 (8-Channel RS-485/422 Card)
The 8-channel RS-485/422 expansion card is shown below in Figure 5-3. This card is default switch
configured to multiplex up to eight data channels onto a single backplane data port (8:1). The 8:1
configuration uses only one backplane data channel from the motherboard but provides the lowest data rate
(maximum 250 Kbaud) per each of the eight channels. Alternatively, 4:4 and 2 x 4:1 options are configurable,
at maximum input channel data rates of 2.5 Mbaud and 400 Kbaud respectively. The 4:4 configuration allows
for the highest data rates but requires four backplane data ports from the motherboard. Refer to configuration
drawing 907-2015-00 for switch settings.
To maintain signal integrity at the high data rates, external cables should be shielded twisted pairs with
120-ohm impedance.
Figure 5-3: 907-485, RS-485/422 Expansion Card
Configure switch SW9 to set the backplane data port used by the 907-485 card. All ports (1~6) are available.
The default setting is data port #1.
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